Low-emissivity coatings are well known in the art. Typically, they include one or two layers of infrared-reflection film and two or more layers of transparent dielectric film. The infrared-reflection film, which generally is a conductive metal like silver, gold, or copper, reduces the transmission of heat through the coating. The dielectric film is used to antireflect the infrared-reflection film and to control other properties and characteristics of the coating, such as color and durability. Commonly used dielectric materials include oxides of zinc, tin, indium, bismuth, and titanium, among others.
Most commercially available low-emissivity coatings have one or two silver layers each sandwiched between two coats of transparent dielectric film. Increasing the number of silver films in a low-emissivity coating can increase its infrared reflection. However, this can also reduce the visible transmission of the coating, and/or negatively impact the color of the coating, and/or decrease the durability of the coating. Perhaps for these reasons, low-emissivity coatings with three silver layers historically have not found much place in the market.
It would be desirable to provide a low-emissivity coating that includes three infrared-reflection layers and has desirable coating properties and characteristics.